Process for preparing magnesium alkyl phenolates



April 9, 1957 R. K. MEYERS ET A1. 2,788,325.

PROCESS FOR PREPARING MAGNESIUM ALKYL PHENOLATES Filed July 27. 195s United States Patent O PROCESS FOR PREPARING MAGNESIUM ALKYL PHENOLATES Richard K. Meyers and Herman D. Kluge, Wappingers Falls, N. Y., assignors to The Texas Company, New York, N. Y., a corporation of Delaware Application July 27, 1953, Serial No. 370,628

7 Claims. (Cl. 252-42.7)

This invention relates to `a process for preparing nongelling oil concentrates `of magnesium salts of high molecular weight alkylated hydroxy aromatic compounds such as alkyl p'henols.

The magnesium salts of alkylated hydroxy aromatic compounds such as alkyl phenols having one or more high molecular weight alkyl side chains substituted on the ring are valuable additives for mineral lubricating oil. Magnesium alkyl phenolates are praticularly useful when used in conjunction with a zinc 4alkyl phenolate as an engine cleanliness additive for airplane engine oil of the highly rened residual type as disclosed and claimed in the copending application of F. C. McCoy, B. L. Benge, E. C. Knowles, and C. C. Towne, Serial No. 286,634, now U. S. Patent 2,674,577, which was tiled May 7, 1952, 'as a continuation-in-part of Serial No. 143,836, led February 11, 1950, which is now abandoned.

Because of their hygroscopic nature, magnesium alkyl phenolates are used in the form of a lube oil concentrate in which the magnesium salt usually constitutes about 15 to 30 weight percent of the total mixture. The use `of a lube oil concentrate of the magnesium alkyl phenolate simplies the incorporation of -the magnesium salt in lubricating fractions in anhydrous form. One of the difficulties encountered in the use of the magnesium alkyl phenolate concentrate is that the concentrate tends to set up in the form of a viscous gel which has inferior solubility in lube oil 'fractions and which is inferior from a quality viewpoint as an engine cleanliness agent.

This application is related to a commonly assigned application, Serial No. 370,627, filed Iuly 27, 1953, in the name of Richard K. Meyers, wherein it is disclosed that the gel-forming tendencies of magnesium alkyl phenolate concentrates are eliminated and prevented by the -addition of 0.2 to 10 weight percent of a solubilizing agent which is a primary or secondary amine, a monoaliphatic glycol ether, an aliphatic alcohol, an `aliphatic mercaptan, an aliphatic ether, an aliphatic sulfide or mixtures thereof. The process of the related application for preventing gel formation in magnesium alkyl phenol-ate concentrates is applicable to concentrates of magnesium sal-ts formed either by the double decomposition procedure or by the direct alcoholate process. In the instant invention, there is disclosed a modication of the direct alcoholate procedure for preparing non-gelling, soluble magnesium `alkyl phenolate concentrates of increased magnesium salt concentration.

In U. S. 2,610,982, which issued September 16, 1952, to John W. Hutcheson, it is disclosed that magnesium salts of high molecular weight alkylated hydroxy aromatic compounds of desired solubility and quality for residual lubricating oil additives are obtained by 4reacting a magnesium alcoholate such as magnesium me'thylate directly with a high molecular Weight alkyl phenol under special critical conditions. In accordance with this patent, the gel-forming tendency of magnesium phenolateV concentrates is eliminated by subjecting the concentrate result- ICC ing from prescribed direct alcoholate reaction to heat treatment at a temperature `of to 180 C. for la period of at least three hours. This invention involves an im proved process for preparing soluble non-gelling high quality magnesium alkyl phenolate concentrates without resorting to a heat treatment. In addition, the concentrates resulting from the process of this yinvention contain 35 to 55 Weight percent magnesium salts as contrasted with the 15 to 30 percent concentration attainable by previous procedures.

In accordance with the process of this invention, magnesium alkyl phenolate concentrates are prepared by reacting under substantially anhydrous conditions an `alkylsubstituted hydroxy aromatic compound with a magnesium salt of an alkoxy alkanol in a lube oil medium and in the presence of excess alkoxy alkanol. The magnesium alkoxy alkoxide is employed in an amount somewhat less than the calculated stoichiometric amount required for the neutralization of the alkyl-substituted hydroxy 4aromatic compound. The reaction mixture is heated at an elevated temperature suiciently high to distill off the excess alkoxy alkanol, but below the boiling point of the lube oil reaction medium. A stripping operation involving contact with a dry gas at a temperature between 100 and 200 C. is advantageously used to cornplete removal of alkoxy alkanol. Nitrogen, dry air and natural gas can be used as the stripping gas. The resulting concentrates contain 35 to 50 weight percent magnesium alkyl phenolate, are free from gel-forming tendencies and display excellent engine detergent characteristics when incorporated in an airplane oil.

An `important feature of the magnesium alkyl phenolate concentrates produced by the process of this invention is their possession of a substantially higher magnesium salt content than concentrates produced by other procedures. The higher salt content of the concentrates is a direct result of the improved oil solubility of the magnesium alkyl phenolates produced by the process of the invention. The improved oil solubility, as evidenced by the 35 to 50 weight percent concentrates produced, lsimpliies the incorporation of the magnesium alkyl phenolates in lube oils as engine cleanliness agents. Lube oil compositions having a higher concentration of magnesium alkyl phenolates can be prepared with the highly soluble magnesium alkyl phenolates of this invention.

The other outstanding feature of the magnesium salt concentrates of this invention is that they do not form highly viscous gels even after standing for long periods of time, for example, six months to a year. The use of the process of this invention completely eliminates the gel-forming tendency which is characteristic of magnesium alkyl phenolate concentrates.

It is postulated that gel formation results from an association of the magnesium phenolate molecules into large aggregates. Apparently, the preparation of the magnesium alkyl phenolate concentrates by reaction o1 an alkyl-substituted phenol with a magnesium alkoxy alkanol in the presence of excess alkoxy alkanol inhibits this `association. The inhibiting action on gel formation obtained by manufacturing magnesium alkyl phenolate concentrates by the process of this invention -is such that the heat treatment of extended duration prescribed in the afore-identifed commonly-owned Hutcheson patent is unnecessary.

Magnesium alkyl phenolates are prepared from alkylated hydroxy aromatic hydrocarbons wherein the substituent aliphatic group or groups, which are either an alkyl or an alkenyl group, on the benzene nucleus contain a total of 15 to 30 carbon atoms. The preferred material from the standpoint of additive manufacture is an alkyl phenol prepared by alkylating a mononuclear monohydroxy compound such as phenol, cresol or other alkyl phenols with anolen polymer such as propylene polymer gontaining from about to 30 carbon atoms.v Alkylated derivatives of mononuclear polyhydroxy aromatic hydrocarbons such as hydroquinone, pyrogallol and other dihydricand trihydricphenols can be employed. From thenstandpoints of availability and economy, alkyl-phenols prepared by alkylating phenol with a Cia to Cso and preferably a Cia to C2G propylene polymer with an `anhydrous HF catalyst or with an AlClz-HSO4 complex catalyst are preferred starting materials for the manufacf.ture of the magnesium alkyl phenolate. Dialkylated phe- :nols in which the total of the carbon atoms in the alkyl ,groups is in the range of 15 to 30 carbon atoms may also be employed for the manufacture of magnesium alkyl phenolates; dinonyl phenol prepared by alkylation of ,phenol with propylene trimer is an example of this type of starting material. `vfAlkoxy alkanols from which the magnesium alkoxy lalkoxides are formed have the general formula ROROH, wherein R is an aliphatic group, which includes alkyl and lkenyl radicals, having l to 5 carbon atoms and R is adivalent acyclic residue which is either an aliphatic hydrocarbon radical having two to six carbon atoms or a polyalkylene polyglycol radical having four to eight carbon atoms. rl`he most widely used alkoxy alkanols are monoaliphatic glycol ethers such as the carbitols and cellosolves. Examples of alkoxy alkanols which may be employed are methoxy ethanol (methyl Cellosolve), ethoxy ethanol (Cellosolve), butoxy ethanol (butyl Cellosolve), monomethyl ether of diethylene glycol (methyl Carbitol), monoalkyl ether of diethylene glycol (monoalkyl Carbitol), monomethyl ether of triethylene glycol, -6-methoxy-1-hexanol and 4-ethoxy-1-butanol. L Referring to the drawing, the magnesium alkoxy alkoxide is formed by reaction of magnesium turnings with an excess of anhydrous alkoxy alkanol. Magnesium turnings are added to the anhydrous alkoxy alkanol in the proportion of about one to three atomic quantities of magnesium per liter of alkoxy alkanol; normally, one to two atomic quantities of magnesium per liter of alkoxy alkanol `are used. By heating under reux, there is obtained a one to three molar clear solution of magnesium alkoxy alkoxide in alkoxy alkanol. The magnesium alkoxy alkoxide is mainly in the form of the neutral magnesium salt having the general formula Mg(OROR)2 wherein R and R' designate the radicals previously identified in the general formula of the alkoxy alkanols although a portion of' the reaction product may be in the form of the basic magnesium salt having the general formula ROR'OMgOH.

A clear solution of magnesium alkoxy alkoxide in alkoxy alkanol is employed as the reagent for reaction with the alkyl phenol since it supplies the excess alkoxy alkanol required in the reaction medium for the production of nongelling highly soluble magnesium alkyl phenolates. The alkoxy alkanol solution of magnesium alkoxy alkoxide is added incrementally to the solution of alkyl phenol and lube oil maintained at the prescribed reaction conditions.

The basic reaction ot' the process of the invention is illustrated by the reaction between an alkyl phenol and magnesium methoxy ethoxide as shown in the following equation: 2RCsH4OH+Mg(OC2H4OCHa)2- n Mg(OC6H4R)z-}-2CH3OC2H40H The magnesium alkyl phenolate-forming reaction is carried out under substantially anhydrous conditions and with somewhat less than the stoichiometric equivalent amount of magnesium alkoxy alkoxide than is required to t arcanes l presence of magnesium alkoxide in the nal product and to givethe proper solubility characteristics.

The amount of alkoxy alkanol employed in the reaction mixture is normally to 125 weight percent of the alkyl phenol employed in the reaction mixture. The use of l to 3 molar alkoxy alkanol solutions of the magnesium salt in the reaction mixture provides the required amount of alkoxy alkanol. The magnesium alkyl phenolate-forming reaction is effected in the presence of a lube oil fraction which may be either parainc or naphthenic in nature. The amount of mineral lubricating oil employed in the reaction mixture is suficient to give-a lube oil concentrate containing between X15 and 30 weight percent magnesium alkyl phenolate. A concentrate containing the desired weight percent of the magnesium alkyl yphenolate is obtained by employing the mineral lubricating oil in an amount equivalent to 0.9 to 2 times the weight of the alkyl phenol added `to the reaction mixture. A refined parathn base distillate motor oil of about SAE 10 Grade or refined naphthene base oil having an SUS viscosity at 100 F. of about 300 are preferred lube oil fractions for the preparation of the magnesium alkyl phenolates in accordance with the process ofthis invention.

The magnesium alkoxy alkoxide is added incrementally to the reaction mixture which is maintained at a temperature suiciently high to effect removal of the alkoxy alkanol added to the reaction mixture as a solubilizing agent and formed during the reaction. Since the temperature is maintained below a level at which the lube oil component of the reaction mixture is distilled, temperatures between and 250 C. are normally employed.

After no more alkoxy alkanol is obtained as a distillate at temperatures. between .100 and 250 C., the reaction mixture is advantageously subjected to a stripping operation involving passage of a dry gas such as nitrogen or air to effect complete removal of the alkoxy alkanol. Temperatures within the prescribed 100 to 250 C. range and usually in the neighborhood of about to 170 C. are employed for the stripping operation. The stripping operation can be made an integral part of the distallation step .wherein the alkoxy alkanol is removed; in this modification the gas is passed through the reaction mixture during the distillation.

After the stripping operation, the concentrate is cooled and there is obtained a non-gelling concentrate of high magnesium alkyl phenolate concentration which is readily solublerin lube oil fractions and which` imparts excellent engine cleanlinessl properties to lube oils in which itis incorporated. It is noteworthy that a high quality nongelling magnesium alkyl phenolate concentrate is obtained by the process of this invention without the necessity of a heat treatment of extended duration.

The following examples illustrate the present invention further: l

EXAMPLE I `166 g. (6.84 mols) of magnesium turnings were reacted with 4,650 ml. of methoxy ethanol; the resulting reaction mixtureA was a'1.47 molar solution of magnesium methoxy/ethoxide in methoxy ethanol. The methoxy ethanol solution of magnesium methoxy ethoxide was slowly added to a mixture comprising 6,850 g. (l5 mols) of a C26 alkyl phenol calculated from the hydroxyl number, and 6,784 g. of a naphthene base distillate lubricating oil having an SUS viscosity at 100 F. of `300, which mixture had been heated to a temperature of 150 C. before addition of the solution of magnesium methoxy ethoxide. The alkyl phenol in the reaction mixture was approximately 10 percent in excess of the stoichiometric amount. The methoxy ethanol solution of magnesium methoxy ethoxide was added at a rate sufficient to maintain a temperature of about 150 C., and the methoxy ethanol was continuously removed by distillation. After the additionwas `completed and methoxy ethanol was no longer obtained` as a distillate, the reaction was maintained at a temperature of 150 C, for one hour `and subsequently subjected to vacuurnbetween and 20 pam. for a period of 3 hours while the temperature was maintained at about 150 C.; the vacuum was obtained by means` of a water aspirator.

A portion, 2,300 g. was subjected to a stripping operation involving bubbling dry `nitrogen therethrough at a temperature of about 300 F. for several hours to yield a nished concentrate substantially free of methoxy ethanol. The concentrate obtained in this manner had a kinematic viscosity at 210 F. of 70.7 and analyzed 1.25 percent magnesium, indicating a magnesium alkyl phenolate concentration of 48.6 weight percent. This magnesium alkyl phenolate concentrate was readily `soluble in lubricating oil fractions and `did `not display any gelforming tendencies even after standing for long periods of time.

EXAMPLE Il 945 g. of a reaction mixture prepared according to Example I were subjected to a different type stripping operation. This portion was subjected to a stripping op eration which involved bubbling air therethrough at `a `temperature of about 150 C. until a sample dissolved in ether failed to give a precipitate in the presence of water. The concentrate obtained by stripping with air which analyzed 1.26 percent magnesium indicating a magnesium alkyl phenolate concentration of 49 weight percent, had a kinematic viscosity at 210 F. of 35.7. This concentrate possessed good solubility in lube oil fractions and was free from gel-forming tendencies even at'ter storage for a considerable period of time.

The effectiveness of the magnesium alkyl phenolate concentrates prepared by the process of the invention was demonstrated in the new airplane oil detergency test. The concentrates prepared as outlined in Examples I and E were evaluated in the new airplane oil detergency test in a residual airplane engine oii having an SUS viscosity at 210 F. of about 120 and designated AEO-120- The new airplane engine oil (AEO) detergency test is conducted on the improved power section version of the CFR high speed engine equipped with a dry sump oil system. A new piston and piston rings are installed for each run and the engine is assembled according to rigid dimensional specifications. Engine operation consists of a three-hour break-in on a residual airplane engine oil having an SUS viscosity at 210 F. of about 120 and designated AEG-420; 11S/145 aviation gasoline is used as fuel at elevated temperatures and power level which simulate current aircraft engine operating practices. Following the test run, the piston is inspected visually on the basis of ring sticking, piston skirt, land, groove and underpiston deposits, and the used oil condition is determined by appropriate analysis.

The improved power section-CFR engine is equipped with a modied cylinder head to provide im proved cooling 'and an aluminum domed short skirt piston similar to aircraft piston design. The test is carried out under the following conditions:

Compression ratio 6.6. Speed, R. P. M 1800. Fuel/air ratio 0.08.

Spark advance, B. T. C-. 15. Coolant out temperature-. 375 F.

Intake oil temperature 190 F.

Inlet oil temperature 185 F.

Fuel 11S/145 aviation gasoline containing 4.58 ml. TEL/ gal.

Duration of run 50 hours.

The oils are evaluated on a demerit rating system which provides a visual means of reducing piston condition to numerical description. A piston area which is new, clean or otherwise in excellent condition is assigned 0 demerits,

Cil

while 10 demerits are assignedltp the worst possible eondition. The piston demerit rating is reported as the total of the ring groove, ring land, underpiston and piston skirt demerits.

In evaluating the ring grooves, demerits are assigned respectively to the thrust and anti-thrust portions of each ring groove; in cases where the deposit conditions vary considerably in any half ring groove, the demerit rating which best describes the over-all condition is assigned. Since stuck rings prevent linspection of the ring groove, a demerit rating of 10 is assigned arbitrarily. The worst possible condition for ring grooves is indicated by a rat ing of 100, resulting from the assignment of a rating of 10 t-o all ring grooves on both thrust and anti-thrust sides. Demerits are assigned to ring lands according to the same schedule used for ring groove deposits, and a rating of represents the worst possible condition. In evaluating underpiston demerits, piston undercrown and underskirt are separately assigned demerits; in evaluating underpiston demerits, the worst possible condition is again represented by a rating of 100. In evaluating piston skirt deposits, demerits are assigned to each of the thrust and anti-thrust sides by noting the percent area covered by deposits and multiplying by the corresponding factor; the demerit per piston is obtained by summing up the demerits assigned to the thrust and anti-thrust sides and dividing by 2.

In the following table, there is shown the electiveness of the magnesium alkyl phenolate concentrates produced in Examples I and II as engine cleanliness agents. The concentrates were incorporated in the percentages shown in AEC-120. The rating of the AEG- base oil is included -for comparison purposes.

New airplane engine detergency test Percent Demerits Concentration of Magnesium salt Oil I Under Skirt Lands Grooves Piston Total AEC-120 AEO-120+4.5% con centrate from Example I. 2. 2 AEO 120+ 2.5% concentrate from Example The excellent solubility of the magnesium alkyl phenolates produced by the process of this invention in lube oil fractions is evidenced by the fact that samples of the oil tested in the previous table were clear solutions after storage for three months. Uniformly satisfactory airplane engine oils have been formed by the incorporation of magnesium alkyl phenolates produced by the process of this invention.

Obviously, many modifications and Variations of the invention as hereinbefore set forth may be made without departing from the spirit and scope thereof and, therefore, only such limitations should be imposed as are indicated in the appended claims.

We claim:

l. In the manufacture of a non-gelling lubricating oil concentrate containing a magnesium salt of an aliphaticsubstituted hydroxy aromatic compound consisting ot' carbon, hydrogen and oxygen and having a hydroxyl group attached to 'the ring and having at least one aromatic nucleus having nuclear-substituted aliphatic substituents having a total of at least 15 carbon atoms, a process which comprises reacting under substantially anhydrous conditions said aliphatic-substituted hydroxy aromatic compound with a magnesium salt ot an alkoxy alkanol of the general formula ROROH, wherein R is an aliphatic group having l to 5 carbon atoms and R' is a divalent acyclic residue selected from. the group consisting of aliphatic hydrocarbon radicals having 2 to 6 carbon atoms and a polyalkylene polyglycol radical having 4 to 8 carbon atoms, said magnesium salt of -alkoxy alkanol reactant being present in said reaction mixture in a quantity iess than the calculated stoichio metric amount required for neutralization of said aromatic compound, eecting said reaction in the presence of alkoxy alkanol and of a lubricating oil fraction, and heating said reaction mixture at mildly elevated tempera tures sufficiently high to remove said alkoxy alkanol by distillation, but below the boiling point orr said lubricating oil fraction with the resulting production of a nongelling lubricating oil concentrate containing a magnesium salt of said aliphatic-substituted hydroxy aromatic compound. t

2. A process according to claim 1 in which Athe reaction mixture is stripped with a dry gas during the distillation step.

3. A process according to claim 1 in which the alkoxy .alkanol present in said reaction mixture is 25 to 125 weight percent of said alkyl-substituted hydroxy aromatic compound.

4. A process according to claim 1 in which said mag- 3 nesium salt is added to said reaction mixture in a 1:3 molar solution of alkoxy alkanol.

5. A process according to claim 1 in which said lubri cating oil fraction present in said reaction mixture comprises 0.9 to 2 times the weight of saidghydroxy aromatic compound.

6. A process according to claim 1 in which said aliphatic-substituted hydroxy aromatic compound is a vmono-alkyl phenol wherein the alkyl group contains between 15 and 30 carbon atoms.

7. A process according to claim 1 in which the reaction mixture is subjected to stripping with a dry gas subsequent to the distillation step wherein alkoxy alkanol is removed.

References Cited in the le of this patent UNITED STATES PATENTS Hutcheson Sept. 16, 1952 Stewart June 1, 1954 OTHER REFERENCES 

1. IN THE MANUFACTURE OF A NON-GELLIONG LUBRICATING OIL CONCENTRATE CONTAINING A MAGNESIUM SALT OF AN ALIPHATICSUBSTITUTED HYDROXY AROMATIC COMPOUND CONSISTING OF CARBON, HYDROGEN AND OXYGEN AND HAVING A HYDROXYL GROUP ATTACHED TO THE RING AND HAVING AT LEAST ONE AROMATIC NUCLEUS HAVING NUCLEAR-SUBSTITUTED ALIPHATIC SUBSTITUENTS HAVING A TOTAL OF AT LEAST 15 CARBON ATOMS, A PROCESS WHICH COMPRISES REACTING UNDER SUBSTANTIALLY ANHYDROUS CONDITIONS SAID ALIPHATIC-SUBSTITUTED HYDROXY AROMATIC COMPOUND WITH A MAGNESIUM SALT OF AN ALKOXY ALKANOL OF THE GENERAL FORMULA ROR''OH, WHEREIN R IS AN ALIPHATIC GROUP HAVING 1 TO 5 CARBON ATOMS AND R'' IS A DIVALENT ACYCLIC RESIDUE SELECTED FROM THE GROUP CONSISTING OF ALIPHATIC HYDROCARBON RADICALS HAVING 2 TO 6 CARBON ATOMS AND A POLYALKYLENE POLYGLYCOL RADICAL HAVING 4 TO 8 CARBON ATOMS, SAID MAGNESIUM SALT OF ALKOXY ALKANOL REACTANT BEING PRESENT IN SAID REACTION MIXTURE IN A QUANTITY LESS THAN THE CALCULATED STOICHIOMETRIC AMOUNT REQUIRED FOR NEUTRALIZATION OF SAID AROMATIC COMPOUND, EFFECTING SAID REACTION IN THE PRESENCE OF ALKOXY ALKANOL AND OF A LUBRICATING OIL FRACTION, AND HEATING SAID REACTION MIXTURE AT MILDLY ELEVATED TEMPERATURES SUFFICIENTLY HIGHLY TO REMOVE SAID ALKOXY ALKANOL BY DISTILLATION, BUT BELOW THE BOILING POINT OF SAID LUBRICATING OIL FRACTION WITH THE RESULTING PRODUCTION OF A NONGELLING LUBRICATING OIL CONCENTRATE CONTAINING A MAGNESIUM SALT OF SAID ALIPHATIC-SUBSTITUTED HYDROXY AROMATIC COMPOUND. 